Cyclometalated rhodium complexes of phenyl- and diphenyl-substituted oxazole and thiazole luminophores

Cyclometaleted rhodium complexes of oxazole and thiazole luminophores Rh(C??N)₂En]Cl (C??N)^?, deprotonated forms of 2,5-diphenyloxazole, 2-phenylbenzothiazole, 2-(biphenyl-4-yl)-6-phenylbenzoxazole, and 2-(biphenyl-4-yl)-5-phenyloxazole; En ?? ethylenediamine] were obtained and characterized by the methods of ¹H NMR, IR, and electron absorption and emission spectroscopy. Two cyclometallated ligands in the inner sphere of the complexes are in the cis-C,C positions. Cyclometallating of the luminophores results both in a red shift of intraligand ??-??*-optical transitions (???? ??1.2 kK) as compared to free luminophores and in the appearance of a long-wave band (??_max 376?C392 nm) of a mixed nature: metal-ligand charge transfer/intraligand transition. Alongside with the internal conversion to a low-energy state of the metal-ligand charge transfer/ intraligand transition, the emission degradation of photoexcitation energy results in the intraligand ??-??*-fluorescence of the complexes (??_max 390?C423 nm) at room temperature.